Cosolvent flushing for the remediation of PAHs from former manufactured gas plants

Abstract

Cosolvent flushing is a technique that has been proposed for the removal of hydrophobic organic contaminants in the subsurface. Cosolvents have been shown to dramatically increase the solubility of such compounds compared to the aqueous solubility; however, limited data are available on the effectiveness of cosolvents for field-contaminated media. In this work, we examine cosolvent flushing for the removal of polycyclic aromatic hydrocarbons (PAHs) in soil from a former manufactured gas plant (FMGP). Batch studies confirmed that the relationship between the soil-cosolvent partitioning coefficient (Ki) and the volume fraction of cosolvent (fc) followed a standard log-linear equation. Using methanol at an fc of 0.95, column studies were conducted at varying length scales, ranging from 11.9 to 110 cm. Removal of PAH compounds was determined as a function of pore volumes (PVs) of cosolvent flushed. Despite using a high fc, rate and chromatographic effects were observed in all the columns. PAH effluent concentrations were modeled using a common two-site sorption model. Model fits were improved by using MeOH breakthrough curves to determine fitted dispersion coefficients. Fitted mass-transfer rates were two to three orders of magnitude lower than predicted values based on published data using artificially contaminated sands.

Historical cancer incidence and mortality assessment in an Illinois community proximal to a former manufactured gas plant

“…As such, considerable literature exists on the methodological, toxicological, elemental chemistry and extracting techniques involving remediation and compound evaluations from abandoned sites. 31–34 While potentially hazardous compounds may have been produced as part of the gas manufacturing process, the extent and level to which compound residues persist at the sites is unclear. In certain cases, potential hazards may be overestimated as samples in some studies have been consistent with background levels or below the assumed level.…”